JP2011107511A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cool a circuit board by using an air flow having reduced suspended matter such as paper powder or dust. <P>SOLUTION: The image forming apparatus includes: a space 100 for substrate arrangement partitioned from an image forming space and a paper feeding space, and formed between a wall part and a cover member 112 facing to the wall part; the circuit board 120 arranged in the state where a plurality of elements are faced to a surface on the cover member 112 side in the space 100 for substrate arrangement; an intake port 102 at least a part of which is positioned on the downside more than a lower side end 121 of the circuit board 120, provided on the wall part side more than the circuit board 120, and opened so that intake air is blown toward the cover member 112; an exhaust port 104 at least a part of which is opened on the upside more than an upper end of an element positioned on the uppermost part, and provided on the cover member 112; and an intake means for sucking the air in the paper feeding space, and blowing the air from the intake port 102 toward the cover member 112 to send the air to the exhaust port 104. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  In an image forming apparatus such as a copying machine or a printer to which an electrophotographic system is applied, an electrostatic latent image formed on a photosensitive drum is developed by a developing device to form a toner image, which is formed on the photosensitive drum. The transferred toner image is transferred onto a recording medium conveyed from the paper supply unit, and the transferred toner image is fixed on the recording medium to form a printed image. Such an image forming apparatus generally employs a cooling structure in order to suppress a temperature rise in the apparatus due to a heat source.

  For example, as a prior art described in the publication, in a power supply unit that includes a charging unit therein and is capable of discharging the power stored in the charging unit, the charging unit is balanced with a cell unit of a capacitor used in the power unit. A technology is disclosed that includes a circuit board and a heat insulating member, and a mechanism that forcibly takes outside air into the heat radiating member of an element mounted on the balance circuit board and performs air cooling (for example, Patent Document 1).

JP 2008-136349 A

  When a fan is used to cool the internal structure of the image forming apparatus, floating substances such as paper dust and dust are blown onto the structure together with the air flow formed by the fan. An object of the present invention is to cool a circuit board by using an air flow in which these floating substances are reduced.

  According to the first aspect of the present invention, an image forming space in which an image forming unit is arranged, a paper feeding space in which a paper feeding unit that supplies paper toward the image forming unit is arranged, the image forming space, and the feeding A substrate placement space defined between a wall portion and an exterior portion facing the wall portion; and a base material provided opposite to the exterior portion in the substrate placement space; A plurality of elements disposed on one side of the circuit board, the circuit board disposed with the plurality of elements directed toward the surface on the exterior portion side, and at least a part of the circuit board below the lower end of the circuit board An intake port that is located on the side of the wall portion relative to the circuit board and opens to blow inhaled air toward the exterior portion, and the plurality of elements provided on the circuit board At least from the top of the topmost element And the exhaust opening provided in the exterior portion and the air in the paper feed space are sucked in, the sucked air is blown from the intake port toward the exterior portion, and the blown air is The image forming apparatus includes an air intake unit that sends the air to the exhaust port through the substrate arrangement space.

According to a second aspect of the present invention, the intake means includes a fan that sucks air from the sheet feeding space;
The air supply part which has an opposing surface part in the position which opposes the said fan, and blows the air suck | inhaled by the said fan on the said opposing surface part, and sends it to the said inlet port. This is an image forming apparatus.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the air introduction unit further includes an image forming unit opening for blowing air from the fan to the image forming unit. is there.

  The invention according to claim 4 is characterized in that the substrate placement space has a bottom portion in which a step where the position where the air inlet is formed becomes a recess is formed. The image forming apparatus described.

  The invention according to claim 5 is characterized in that the exterior portion has a protrusion extending from the surface facing the circuit board toward the circuit board and extending in the width direction of the circuit board. 5. The image forming apparatus according to any one of 1 to 4.

According to the first aspect of the present invention, compared with the case where the present configuration is not provided, it is possible to reduce the floating matter blown with the sucked air and cool the circuit board.
According to invention of Claim 2, compared with the case where it does not have this structure, the influence of a suspended | floating matter can be reduced more.
According to invention of Claim 3, compared with the case where it does not have this structure, structures other than a circuit board can also be cooled together.
According to invention of Claim 4, compared with the case where it does not have this structure, the influence of a suspended | floating matter can be reduced more.
According to the fifth aspect of the present invention, the elements of the circuit board can be cooled more efficiently than in the case where the present configuration is not provided.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a front view of the space for board | substrate arrangement | positioning which concerns on this Embodiment, and an intake means. It is a side view of the space for board | substrate arrangement | positioning concerning this Embodiment. It is a perspective view of the air intake means which concerns on this Embodiment. It is the perspective view which decomposed | disassembled a part of air intake means which concerns on this Embodiment.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram showing an image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 includes an image forming space 10, a paper feed space 90, and a substrate placement space 100.
The image forming apparatus 1 includes a plurality of image forming units 30 (30Y) of yellow (Y), magenta (M), cyan (C), and black (K) as an aspect of the image forming unit disposed in the image forming space 10. , 30M, 30C, 30K). Each image forming unit 30 (30Y, 30M, 30C, 30K) includes a photosensitive drum (image holding member) 31 and various electrophotographic devices sequentially arranged around the photosensitive drum 31. It is integrally formed and is a so-called cartridge. The integrally formed electrophotographic device includes, for example, a charging roll 32 for charging the photosensitive drum 31 and an electrostatic latent image formed by exposure on the photosensitive drum 31 charged by the charging roll 32. A developing device 33 for developing the toner, a cleaning device 35 for removing waste toner on the photosensitive drum 31, and the like.

Further, the image forming apparatus 1 includes an exposure unit 40 that exposes each photosensitive drum 31 using, for example, laser light as one aspect of the image forming unit. Further, as one mode of the image forming unit, an intermediate transfer belt 51 on which each color toner image formed on the photosensitive drum 31 of each image forming unit 30 (30Y, 30M, 30C, 30K) is transferred in a multiple manner, and each image A primary transfer roll 52 that sequentially transfers (primary transfer) each color toner image formed by the forming unit 30 (30Y, 30M, 30C, 30K) to the intermediate transfer belt 51 is provided. Furthermore, as an aspect of the image forming unit, a secondary transfer roll 80 that batch-transfers (secondary transfer) toner images formed on the intermediate transfer belt 51 onto a sheet P that is a recording material (recording paper). I have. Further, as these image forming units, a fixing unit 81 for fixing the secondly transferred toner image on the paper P is provided.
The image forming apparatus 1 includes a toner cartridge 20 that supplies toner to the developing device 33 of each image forming unit 30 (30Y, 30M, 30C, 30K). In addition, the image forming apparatus 1 includes a control unit 83 that controls the entire image forming apparatus 1. Further, the image forming apparatus 1 includes a paper feed cassette 93 that is one mode of a paper feed unit in a paper feed space 90 partitioned from the image forming space 10.

  The image forming apparatus 1 executes a series of image forming processes under operation control by the control unit 83. That is, image data acquired from a PC, a scanner, or the like is subjected to image processing by an image processing unit (not shown) and sent to the exposure unit 40 as image data of each color. Each image forming unit 30 (30Y, 30M, 30C, 30K) receives exposure by the exposure unit 40 and forms toner images of each color by an electrophotographic method. Each color toner image formed on the photosensitive drum 31 of each image forming unit 30 (30Y, 30M, 30C, 30K) is sequentially electrostatically transferred (primary transfer) onto the intermediate transfer belt 51 by the primary transfer roll 52. A superimposed toner image in which the toners of the respective colors are superimposed is formed. The superimposed toner image on the intermediate transfer belt 51 is conveyed to a secondary transfer portion where the secondary transfer roll 80 is disposed as the intermediate transfer belt 51 moves. On the other hand, the paper P is fed from the paper feed cassette 93 in accordance with the transport timing of the superimposed toner image and transported to the secondary transfer area. The superimposed toner image on the intermediate transfer belt 51 is collectively electrostatically transferred (secondary transfer) onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 80 in the secondary transfer portion. Is done. The sheet P on which the superimposed toner image has been electrostatically transferred is conveyed to the fixing unit 81 and fixed on the sheet P by the fixing unit 81. The paper P after fixing is conveyed to a paper stacking unit provided in the discharge unit of the image forming apparatus 1.

Next, cooling in the substrate placement space 100 performed in the image forming apparatus 1 will be described with reference to FIGS. 1 to 5.
Here, FIG. 2 is a configuration diagram for explaining the substrate placement space 100 in the image forming apparatus 1 according to the present embodiment. 3 is a configuration diagram for explaining the substrate placement space 100 from the left side of the configuration diagram of FIG. 3, illustration of the transverse members 113 and 115 and the duct inclined member 135 shown in FIG. 2 is omitted. FIG. 4 is a perspective view for explaining the fan 130 and the duct 131 shown in FIGS. 2 and 3. FIG. 5 is an exploded perspective view of a part of the duct 131 shown in FIG.

  A substrate placement space 100 shown in FIG. 2 has a space separated from the image forming space 10 and the paper feeding space 90, and is formed, for example, on the back side of the image forming apparatus 1 shown in FIG. As shown in FIGS. 2 and 3, the circuit board 120 including the elements 122 is arranged in the board arrangement space 100. Further, the image forming apparatus 1 includes a fan 130 and a duct 131 as an example of an air intake unit. The fan 130 is connected to the board placement space 100 by a duct 131.

The circuit board 120 is arranged in a state in which the circuit board 120 is erected in the vertical direction (for example, the vertical direction) in the board arrangement space 100.
The substrate placement space 100 is partitioned by a wall member 110 that is an example of a wall portion and a cover member 112 that is an example of an exterior portion. The substrate placement space 100 has an intake port 102 below the wall member 110 and an exhaust port 104 above the cover member 112.

  Further, in the present embodiment, the image forming apparatus 1 is provided on one side surface (for example, the back surface side in FIG. 1) of the image forming apparatus 1 and rotates by receiving an electric driving force to generate an air flow. It has a fan 130 to be formed. Further, the image forming apparatus 1 includes ducts 131 that are respectively connected to the fan 130 and the substrate placement space 100 on one side surface (for example, the back side surface in FIG. 1) of the image forming device 1. The duct 131 divides the air formed from the fan 130 and guides it to the substrate placement space 100 and a drive unit (not shown) of the image forming unit. As will be described in detail later, in the present embodiment, the air present in the sheet feeding space 90 of the image forming apparatus 1 passes through the duct 131 by the rotation of the fan 130 and then passes from the intake port 102 to the exhaust port 104. The plurality of elements 122 provided on the circuit board 120 in the board placement space 100 are cooled.

  As shown in FIG. 3, the circuit board 120 in the present embodiment is fixed to a mounting leg 124 provided on the wall member 110, and the circuit board 120 is arranged in the vertical direction in the board arrangement space 100. In the present embodiment, the circuit board 120 is arranged in the vertical direction. However, if the air flow from the fan 130 flows along the surface of the circuit board 120, for example, the circuit board 120 is inclined in the up-down direction. Other modes, such as placement, can be employed.

  The circuit board 120 includes a plurality of elements 122 on a board surface 120 </ b> A (see FIG. 3) that is a surface facing the cover member 112. Here, the circuit board 120 in the present embodiment is a low voltage application board, and as the element 122, for example, a voltage supply element for applying a voltage of 24V or the like is disposed. The element 122 is, for example, a main control element such as a hard disk, CPU, or memory, or an external connection element that is connected to an external device of the image forming apparatus 1 such as a facsimile or a USB (Universal Serial Bus) device. An element etc. may be sufficient and it is not limited to an element for voltage supply. Therefore, although the circuit board 120 is a low voltage application board in the present embodiment, it is not limited to the low voltage application board. The number of elements 122 provided on the circuit board 120 may be singular or plural.

  The substrate placement space 100 is a space defined by the wall member 110 and the cover member 112 as described above. Further, the substrate placement space 100 is partitioned by further using a bottom member 114, which is an example of a bottom portion, an upper member 116, and lateral members 113 and 115 (see FIG. 2).

Here, the wall member 110 is a member that constitutes one surface of the substrate placement space 100 and functions as a partition that partitions the interior of the image forming apparatus 1. The wall member 110 has a surface facing the circuit board 120. The circuit board 120 is disposed substantially parallel to the wall member 110 and faces the wall member 110.
The cover member 112 is provided to face the circuit board 120 and is provided on the opposite side of the wall member 110 with the circuit board 120 interposed therebetween. In the present embodiment, the cover member 112 is configured as a member independent of the main body cover 1A of the image forming apparatus 1, but may be configured integrally with the main body cover 1A.

  As shown in FIG. 2, the bottom member 114 is provided between the wall member 110 and the cover member 112, and constitutes one surface on the lower side of the substrate placement space 100. Here, in the present embodiment, the bottom member 114 is formed with a step 107. The step 107 is located between the wall member 110, the cover member 112, and the lateral member 115 to form a recess 108. In the present embodiment, the air inlet 102 is formed in the wall member 110 facing the recess 108 (see FIGS. 2 and 3). The recess 108 is configured to accommodate a suspended matter that falls from the inflowing air (details will be described later).

  As shown in FIG. 2, the upper, lower, left, and right directions of the circuit board 120 are members parallel to the upper end face, the lower end face, the left end face, and the right end face of the circuit board 120, respectively. Surrounded by More specifically, the upper member 116 is surrounded by an upper member 116 parallel to the upper end surface, a bottom member 114 parallel to the lower end surface, a transverse member 113 parallel to the left end surface, and 115 parallel to the right end surface. ing.

  An air inlet 102 is formed below the substrate placement space 100, and the air inlet 102 can take in air in the paper feed space 90 inside the image forming apparatus 1. In the present embodiment, air inlet 102 is provided below wall member 110. More specifically, at least a part of the air inlet 102 is configured to open below the horizontal position where the lower end 121 of the circuit board 120 is located. In the present embodiment, the air inlet 102 opens so as to face the cover member 112.

  On the other hand, an exhaust port 104 is provided in the upper part of the substrate placement space 100, and the exhaust port 104 communicates with the outside of the image forming apparatus 1 so that air in the substrate placement space 100 can flow out. . In the present embodiment, the exhaust port 104 is provided on the upper side of the cover member 112. In the present embodiment, among the plurality of elements 122 arranged on the circuit board 120, at least a part of the exhaust port 104 is opened above the horizontal position where the upper end 122A of the uppermost element 122 is located. Is configured to do.

As shown in FIG. 3, a plurality of ribs 106 are formed in the substrate placement space 100 of the image forming apparatus 1 as protrusions that partition the substrate placement space 100. In the present embodiment, the plurality of ribs 106 are formed so as to extend from the inner side of the cover member 112 (the side facing the circuit board 120) toward the circuit board 120. The plurality of ribs 106 extend in the width direction of the circuit board 120 (for example, the direction perpendicular to the paper surface in FIG. 2), and are further formed in the vertical direction of the base circuit board 120. For example, the plurality of ribs 106 extend in the width direction by a distance longer than the width of the circuit board 120. More preferably, it extends to the vicinity of the width of the substrate placement space 100 defined by the transverse members 113 and 115 (see FIG. 2). The plurality of ribs 106 narrow the gap formed between the circuit board 120 (and the element 122), so that the air between the circuit board 120 and the cover member 112 is upward on the circuit board 120 side. It is arranged to flow.
The plurality of ribs 106 can be formed by bending a metal plate, but the material and structure are not particularly limited as long as the air flow can be suppressed.

Furthermore, the image forming apparatus 1 according to the present embodiment includes the fan 130 that forms an air flow as described above. In the present embodiment, one surface 130 </ b> A (see FIG. 3) of the fan 130 faces the paper feed space 90 so that the fan 130 takes in air inside the paper feed space 90 provided in the image forming apparatus 1. Is provided. Further, the other surface 130 </ b> B (see FIG. 3) of the fan 130 is provided facing the inside of the duct 131.
As shown in FIG. 1, in the present embodiment, the paper feed space 90 is formed by an arrangement space of a paper feed cassette 93 provided on the bottom side of the image forming apparatus 1. The fan 130 is disposed facing the paper feed space 90 from the back side in FIG.

Furthermore, the image forming apparatus 1 of the present embodiment has a duct 131 as follows.
As shown in FIGS. 4 and 5, the duct 131 is connected to a fan 130 disposed so as to face the duct wall portion 134 in the vicinity of the central portion in the horizontal direction.
The duct 131 is configured continuously with the air inlet 102 so that the air inside the paper feed space 90 taken in by the fan 130 flows into the air inlet 102. The duct 131 in the present embodiment includes a duct wall 134 to which the wind from the fan 130 is blown, a duct inclined member 135 that is connected to the duct wall 134 and guides the wind to the air inlet 102, and a lower side of the duct 131. A duct top portion 138 connected to the duct bottom portion 136, the duct wall portion 134, the fan 130 and the like constituting one surface is formed. The duct bottom 136 is configured to include a duct recess 140 that accommodates suspended matter falling from the inflowing air.

  Furthermore, the duct 131 in the present embodiment includes a drive unit cooling port 137. The driving unit cooling port 137 is provided to cool a driving unit (not shown) such as a stepping motor that drives an image forming unit (for example, the photosensitive drum 31). As shown in FIGS. 4 and 5, the driving unit cooling port 137 is disposed on the opposite side of the air inlet 102 with respect to the fan 130. In the present embodiment, the drive unit cooling port 137 is open toward the upper side of the duct 131 and is configured to allow air to flow out toward the drive unit of the image forming unit located above the duct 131. .

Next, the flow of air for cooling the element 122 provided on the circuit board 120 will be described with reference to FIGS.
In the present embodiment, the fan 130 forms an air flow by an electric driving force, so that the air inside the paper feed space 90 flows into the duct 131. Here, floating substances such as paper dust and dust exist in the paper feed space 90, and this floating substance may also flow into the duct 131 together with air.
In the present embodiment, a configuration is adopted in which air is taken in from the paper feed space 90 partitioned from the image forming space 10. Therefore, the possibility that a conductive floating substance (for example, a part of a static elimination brush (not shown)) generated from the image forming unit arranged in the image forming space 10 is taken in together with air is reduced.
In FIG. 1, the air formed by the fan 130 flows toward the back side in the figure. The air that has flowed into the duct 131 is blown against the duct wall portion 134 to reduce the wind speed and branch in a different direction (see arrows I and IV in FIG. 2). The branched air flows toward the intake port 102 and the drive unit cooling port 137, respectively.

  First, one air branched to the drive unit cooling port 137 flows from the drive unit cooling port 137 to the drive unit (not shown) of the image forming unit disposed in the image forming space 10 to cool the drive unit. . The air that has cooled the drive unit of the image forming unit is discharged out of the apparatus through an exhaust opening (not shown) provided in the main body cover 1A on the upper side of the image forming apparatus 1, for example.

  The other branched air travels toward the air inlet 102 and first rises along the duct inclined member 135 and is blown to the duct upper portion 138. Then, after the wind speed decreases, the direction of the air flow is changed and flows from the duct 131 into the board placement space 100 through the air inlet 102 (see arrow I in FIGS. 2 and 3).

The air that has flowed into the board placement space 100 is blown against the cover member 112, and the wind speed is lowered. Cool (see arrow II in FIGS. 2 and 3). At this time, the rib 106 causes the rising air to flow in a narrow space on the circuit board 120 (and the element 122) side, thereby enhancing the cooling effect of the element 122.
Then, the air rising along the circuit board 120 and reaching the upper end side of the substrate placement space 100 flows out of the substrate placement space 100, that is, outside the image forming apparatus 1 from the exhaust port 104 (FIG. 2). And see arrow III in FIG. 3).

  Here, in the present embodiment, the direction of the air flow restricted by the intake port 102 is matched with the direction of the air flow restricted by the exhaust port 104 (toward the right side in FIG. 3). The direction of these air flows is made to coincide with the arrangement direction of the elements 122 with respect to the circuit board 120.

  Further, as described above, the air taken in by the fan 130 from the inside of the paper feed space 90 is blown to the duct wall portion 134, and the wind speed is reduced in the vicinity of the duct wall portion 134. As the air velocity decreases, the suspended matter taken together with the air from the paper feed space 90 falls. In other words, the suspended matter is knocked down by the duct wall 134. In order to suppress the fallen suspended matter from being rolled up again by the air flow, the duct recess 140 accommodates the suspended matter.

  Similarly, the air taken into the substrate placement space 100 through the air inlet 102 is blown to the cover member 112, and the wind speed decreases near the cover member 112. As the air velocity decreases, the suspended matter taken into the substrate placement space 100 falls with the air. In other words, the suspended matter is knocked down by the cover member 112. In order to prevent the fallen suspended matter from being rolled up again by the air flow, the recess 108 accommodates the suspended matter. The concave portion 108 is a floating substance that falls when the air blown to the cover member 112 rises along the circuit board 120 and a floating substance that falls when the air is blown to the plurality of ribs 106. Can also be accommodated.

  As described above, in the present embodiment, the air taken in from the inside of the paper feed space 90 changes its direction of flow at the duct wall portion 134, the cover member 112, etc., so to speak, some inflection points of the air flow are formed. After that, the element 122 is reached. Then, at the bending point, the speed of the air decreases and the suspended matter falls from the air. Therefore, the influence (for example, a short circuit) on the element 122 caused by floating substances such as dust and paper dust included in the air taken in from the sheet feeding space 90 attached to the element 122 provided on the circuit board 120 is suppressed. be able to.

  Furthermore, in this embodiment, the element 122 of the circuit board 120 is cooled by taking in air from the paper feed space 90 by the fan 130, but the air flow from the fan 130 is not directly directed to the element 122. By blowing on the cover member 112 or the like, the air flow is diverged so that it is directed toward the element 122. By diverging the air flow from the fan 130, it is possible to diffuse the air flow not to a part of the substrate placement space 100 but to the whole. Therefore, the element 122 provided at any location in the substrate placement space 100 can be more reliably cooled. That is, the entire interior of the substrate placement space 100 in the present embodiment can be cooled.

  In the present embodiment, the configuration including the duct 131 has been described. However, the configuration may be such that the air from the fan 130 directly flows into the intake port 102 without including the duct 131. In this case, the air taken in from the inside of the paper feed space 90 by the fan 130 is directly blown onto the cover member 112.

  Further, in the present embodiment, as shown in FIG. 1, the substrate arrangement space 100 is described as being arranged near the back side of the image forming apparatus 1, but the substrate arrangement space 100 in the image forming apparatus 1 is described. The position is not particularly limited as long as it is close to the outer wall portion of the image forming apparatus 1, that is, on the outer ring side, and may be, for example, the left side surface, front surface, rear surface, etc. in the image forming apparatus 1.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image formation space, 90 ... Paper feed space, 93 ... Paper feed cassette, 100 ... Substrate arrangement space, 102 ... Air intake port, 104 ... Exhaust port, 106 ... Rib, 108 ... Recessed part, 110 ... Wall member, 112 ... Cover member, 120 ... Circuit board, 122 ... Element, 130 ... Fan, 131 ... Duct, 137 ... Drive part cooling port, 140 ... Duct recess

Claims (5)

An image forming space in which an image forming unit is disposed; and
A paper feed space in which a paper feed unit that supplies paper toward the image forming unit is disposed;
The image forming space and the paper feed space are partitioned, and a substrate placement space formed between a wall portion and an exterior portion facing the wall portion;
Provided facing the exterior portion in the substrate placement space, and a plurality of elements are disposed on one surface of the base material, and the plurality of elements are disposed in a state facing the surface on the exterior portion side. A circuit board,
An air inlet that is located at least partially below the lower end of the circuit board and that is provided closer to the wall than the circuit board and opens so that the sucked air is blown toward the exterior part When,
An exhaust port provided at least partially above the upper end of the uppermost element of the plurality of elements provided on the circuit board and provided in the exterior part;
An air intake unit that sucks air in the paper feed space, blows the sucked air from the air inlet toward the exterior portion, and sends the blown air to the air outlet through the substrate placement space. Forming equipment. The intake means is
A fan for sucking air from the paper feed space;
The air supply part which has an opposing surface part in the position which opposes the said fan, and blows the air inhaled by the said fan on the said opposing surface part, and sends to the said inlet port. Image forming apparatus.   The image forming apparatus according to claim 2, wherein the air introduction unit further includes an image forming unit opening that blows air from the fan to the image forming unit.   4. The image forming apparatus according to claim 1, wherein the substrate placement space has a bottom portion in which a step where the position where the air inlet is formed becomes a recess is formed. 5.   The said exterior part has a protrusion extended toward the said circuit board from the surface on the side facing the said circuit board, and extended | stretched in the width direction of the said circuit board. The image forming apparatus described.

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